Problem with batch exporting from FCP.

Hello, our editor is using FCP 7.03 on a MacPro 2.8ghz Quad core

Recently when batch exporting clips from FCP more and more clips are coming out White (ie. no moving pics just white screen - audio does come across).

About a month ago we would get perhaps2 white clips out of 200 clips. The problem has been getting worse. Today every second clip was white and our editor had to manually export each of them to ensure it worked.

He is cutting in 1920x1080 ProResHQ 25fps. The output file codec or frame size doesn't affect whether it comes out white or not (we've tried all sorts).

The only recent update of software was the security update thru Software Update yesterday.

Any ideas anyone? Thanks for reading this question.

cheers, liz